Nuclear fission hafnium

Hafnium has only a few applications. Probably its most important use is in nuclear power plants. A nuclear power plant is a facility where energy released from nuclear fission reactions is used to generate electricity. 

The physical property of greatest interest for hafnium is how it responds to neutrons. A neutron is a very small particle found in the nucleus (center) of an atom. Neutrons are used to make nuclear fission reactions occur. Nuclear fission reactions take place when a neutron strikes a large atom, such as an atom of uranium. The neutron makes the atom break apart. In the process, a large amount of energy is released. That energy can be converted to electricity. 

In order to make electricity from nuclear fission, the fission reaction must be carefully controlled. To do that, the number of neutrons must also be kept under close control. Hafnium has the ability to absorb ( soak up ) neutrons very easily. It is used in rods that control how fast a fission reaction takes place. This property is one of the few ways in which hafnium differs from zirconium. Although hafnium is very good at... 

Heat generation takes place in the reactor core of a nuclear plant (Figure 23.15). The core contains the fuel rods, which consist of fuel enclosed in tubes of a corrosion-resistant zirconium alloy. The fuel is uranium (IV) oxide (UO2) that has been enriched from 0.7% the natural abundance of this fissionable isotope, to the 3% to 4% required to sustain a chain reaction. Sandwiched between the fuel rods are movable control rods made of cadmium or boron (or, in nuclear submarines, hafnium), substances that absorb neutrons very efficiently. 

C. Remigius Fresenius once again deserves credit for noting, toward the middle of the nineteenth century, that new analytical techniques invariably lead to fresh sets of discoveries. Whereas the element germanium was found on the basis of "classical methods (Clemens Winkler, 1886), Fresenius observation clearly applies to the discovery of the alkali metals rubidium and cesium (by Robert W. Bunsen after he and G. R. Kirch-HOFF first developed emission spectroscopy in 1861). Other relevant examples include the discoveries of radium and polonium (by Madame Curie), hafnium (Hevesy and Coster, 1922), and rhenium (1. Tacke and W. Noddack, 1925), all with the aid of newly introduced X-ray spec-trometric techniques. This is also an appropriate point to mention the discovery of nuclear fission by Otto Hahn and Fritz Strassmann (19. 8), another accomplishment with strongly analytical characteristics 110]. 

Hafnium has a great affinity for absorbing slow neutrons. This attribute, along with its strength and resistance to corrosion, makes it superior to cadmium, which is also used for making control rods for nuclear reactors. This use is of particular importance for the type of nuclear reactors used aboard submarines. By moving the control rods in and out of a nuclear reactor, the fission chain reaction can be controlled as the neutrons are absorbed in the metal of the rods. The drawback to hafnium control rods is their expense it costs approximately one million dollars for several dozen rods for use in a single nuclear reactor. 

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